Framerate going down when connected to beamer

Since long time I have this problem and now I want to try to get that fixed. I work on a 2 Screen-Computer, showing the stage on the second monitor in fullframe. Everything is fine. As soon as I connect my beamer and show the stage on the beamer my framerate goes massive down. Is there any different scaling happening when the output is to the beamer that causes the problem?

Hello Mark,
I am on Windows and use 2.0.5. I tried "Disable Vertical Retrace Sync" but it didnt change anything. What I wanted to do anyway is to replace all CPU-actor by GPU-actors an now the framerate is incredibly stable! :)